Core-shell ZIF-8@MIL-68(In) derived ZnO nanoparticles-embedded In2O3 hollow tubular with oxygen vacancy for photocatalytic degradation of antibiotic pollutant

Developing a novel core-multishelled metal oxide hollow tube with rich oxygen vacancy is highly attractive in photocatalytic degradation of antibiotic pollutant. Herein, ZnO@In2O3 core-shell hollow microtubes were synthesized via one-step calcination of ZIF-8@MIL-68(In) formed by an in-situ self-assembly. TEM images demonstrate that 0D ZnO quantum dots (QDs) shell with 0.2 µm were well coated on the surface of 1D In2O3 hollow tube as the core with 1.2 µm. The synthesized heterostructure indicates the enhanced photocatalytic performance in tetracycline (TC) degradation compared with single ZIF-derived ZnO and MIL-68(In)-derived In2O3 under simulated solar irradiation. Besides, organic pollutants including malachite green (MG), methylene blue (MB) and rhodamine B (RhB) are further used to evaluate the photocatalytic activity of ZnO@In2O3, and the effect of weight ratios between ZnO and In2O3 on degradation efficiency is also studies. The ZnO@In2O3 heterojunction can provide higher specific surface area, expose more active sites, possess appropriate number of oxygen vacancies, enhance light absorption and further effectively boost the transfer and separation of photoinduced charge carriers. In addition, the proposed photocatalytic mechanism and degradation pathway are discussed in detail based on active species trapping test, electron spin resonance (ESR) and LCMS.